s1_read_last_two_bytes_of_a_mbr_backup_file() { 
	local file_path=$1 
	local last_bytes=$(tail -c 2 "$file_path" | od -A n -t x1 | tr -d ' \n') 
	if [ "$last_bytes" = "55aa" ];then 
		echo "YES" 
	else 
		echo "NO" 
	fi 
} 
s2_read_mbr_partition_table_info() { 
	for i in {0..3}; do 
		offset=$((446 + i * 16)) 
		start_sector=$(dd if="$1" bs=1 skip=$((offset + 8)) count=4 2>/dev/null | od -t u4 -An | tr -d ' \n') 
		if ! [[ $start_sector =~ ^[0-9]+$ ]];then 
			continue 
		fi 
		if [ "$start_sector" -eq 0 ];then 
			continue 
		fi 
		size_sector=$(dd if="$1" bs=1 skip=$((offset + 12)) count=4 2>/dev/null | od -t u4 -An | tr -d ' \n') 
		end_sector=$((start_sector + size_sector - 1)) 
		echo "$start_sector $end_sector" 
	done 
} 
s3_parse_partition_info(){ 
	fdisk_output=$(cat) 
	disk_size_bytes=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $5}') 
	disk_size_sectors=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $7}') 
	physical_sector_size=$(echo "$fdisk_output" | grep "Sector size" | awk '{print $4}') 
	first_partition_start_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $3}') 
	first_partition_end_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $4}') 
	first_partition_type=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $8}') 
	echo "disk size in bytes:$disk_size_bytes" 
	echo "disk size in sectors:$disk_size_sectors" 
	echo "physical sector size in bytes:$physical_sector_size" 
	echo "first partition start sector id:$first_partition_start_sector" 
	echo "first partition end sector id:$first_partition_end_sector" 
	echo "first partition type:$first_partition_type" 
} 
s4_run_passwd_as_plain_user_and_get_status() { 
	oversleeping_path=$(which oversleeping) 
	chown root "$oversleeping_path" 
	chmod 4755 "$oversleeping_path" 
	oversleeping & 
	ps -o uid,euid,ruid -C oversleeping | awk 'NR>1 {print $1","$2","$3}' 
} 
s5_add_a_scheduled_task() { 
	touch $HOME/test_crontab; 
	echo "*/5 * * * * date +\%Y\%m\%d_\%H\%M\%S >> $HOME/test_crontab" | crontab - 
}